Question

PLEASE HELP I'll fan and medal
Find an equation for the nth term of the arithmetic sequence.

-15, -6, 3, 12, ...

Answer 1

@phi

Answer 2

@mayankdevnani

Answer 3

\[\large \bf a_n=a+(n-1)d\]

Answer 4

can you identify the value of a,n and d ?

Answer 5

where a=first term
n=nth term
d=common difference

Answer 6

Is -15 the first term?

Answer 7

And can you show me how to find the common difference again? I keep forgetting

Answer 8

yea! a=-15
remember :-
common difference is difference between any two consecutive terms
so,
d=-6-(-15)=-6+15=9

Answer 9

understood?

Answer 10

Yes that makes so much sense thank you

Answer 11

So then the equation would look like a-15=a(-15-1)9?

Answer 12

@mayankdevnani

Answer 13

I got -7

Answer 14

Oh wait I didn't do the other side yet

Answer 15

\[\large \bf a_n=-15+(n-1)9\]
simplify it

Answer 16

9n-24?

Answer 17

@yanasidlinskiy

Answer 18

Can you help me please

Answer 19

Choices

an = -15 + 9(n + 1)
an = -15 x 9(n - 1)
an = -15 + 9(n + 2)
an = -15 + 9(n - 1)

Answer 20

maya posted the answer
\[ a_n=-15+(n-1)9 \]

the last term is (n-1) times 9
as you know, you can switch the order when multiplying
example: 2*3 = 3*2
all your answers show the 9 first, but that is not problem:
switch the order:
\[ a_n=-15+9(n-1)\]